The present invention relates to a power module having a self protection function. The term "power module" as used herein means a unit comprising power elements such as power transistors and other function, for example, a control unit stored in a single package.
Heretofore, there has been known an intelligent power module as a power module having a self protection function. The term "intelligent power module" (to be simply referred to as "power module" hereinafter) as used herein generally means a module comprising power elements such as power transistors and a control unit for driving and controlling the power elements stored in a single package.
For instance, a prior art power module 2 disclosed by Japanese Laid-open Patent Application No. 10-267977 and shown in FIG. 4 comprises power elements 4 for driving a motor 1, power element drive means 3 for driving and controlling the power elements 4 and self protection means 5 having a self protection function.
The self protection means 5 protects the power module 2 from a plurality of predetermined abnormal phenomena and outputs an abnormality detection signal to the outside when it detects an abnormal phenomenon.
The power element drive means 3 drives and controls the power elements 4 based on a drive signal from an external unit and the output of the self protection means 5.
As shown in FIG. 5, the self protection means 5 comprises an overcurrent protection circuit 51 for protecting the power elements 4, for example, when a current higher than a predetermined current value runs through the power elements 4 incorporated in the power module 2, a short-circuit protection circuit 52 for protecting the power elements 4 or a circuit connected to the power elements 4 when a short-circuit accident occurs in the power elements 4, a control power voltage drop protection circuit 53 for protecting the power module 2 when a control power voltage supplied to the power module 2 falls, an excessive temperature protection circuit 54 for protecting the module from an excessive temperature in the power module 2, and a decoder 55 for decoding binary signals from the above protection circuits 51 to 54 to generate an abnormality detection signal and supplying it to a plurality of output terminals F1 to F3 as a binary signal.
That is, the protection circuits 51 to 54 are incorporated in the power module 2 to cope with a plurality of predetermined abnormal phenomena, and the self protection means 5 outputs an abnormality detection signal to the external unit through the output terminals FOI to FO3 when the protection circuit 51 to 54 fulfill their self protection functions.
When the plurality of the protection circuits 51 to 54 fulfill their functions independently, a protection circuit fulfilling its function is identified by an abnormality detection signal and reported. When two or more protection circuits fulfill their functions at the same time to cope with a plurality of abnormal phenomena which occur at the same time, they are reported with abnormality detection signals at a time.